On a display device such as cathode ray tube display device (CRT), plasma display panel (PDP), electro-luminescence display (ELD) and liquid crystal display device (LCD), the antireflection film is generally disposed on the outermost surface of the display so as to prevent the reduction in contrast due to reflection of external light or prevent entering of an image by reflection.
In general, such an antireflection film is produced by forming a low refractive index layer to an appropriate thickness on a support, in which the refractive index of the low refractive index layer is lower than that of the support. In order to realize a low reflectance, a material having a refractive index as low as possible is preferably used for the low refractive index layer. Furthermore, the antireflection film is used on the outermost surface of a display and therefore, this film is required to have high scratch resistance. In order to realize high scratch resistance of a thin film with a thickness of about 100 nm, strength of the film itself and tight adhesion to the lower layer are necessary.
For lowering the refractive index of a material, techniques of (1) introducing a fluorine atom and (2) decreasing the density (introducing voids) may be used, however, in both of these techniques, the film strength or the adhesive property at the interface is liable to decrease and low scratch resistance results. Thus, it has been difficult to realize a low refractive index and a high scratch resistance at the same time.
As described in JP-A-2002-265866 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) and JP-A-2002-317152, the film strength may be increased to a certain extent by a method of using a fluorine-containing sol-gel film, however, this method causes large restrictions, for example, (1) curing requires heating over a long time and the load of production is large or (2) the film has no resistance against a saponification solution (alkali treatment solution) and in the case of saponifying the TAC surface, this treatment cannot be performed after the antireflection film is formed.
On the other hand, JP-A-11-189621, JP-A-11-228631 and JP-A-2000-313709 describe a technique of introducing a polysiloxane structure into a fluorine-containing polymer to reduce the friction coefficient on the film surface and thereby improve the scratch resistance. This technique is effective to a certain extent for the improvement of scratch resistance, however, in the case of a film lacking in the substantial film strength and interface adhesion, a sufficiently high scratch resistance cannot be obtained only by this technique.